$ C = \left[\begin{array}{rrr}0 & -2 & 4 \\ 0 & 3 & -1 \\ 0 & 4 & 3 \\ 1 & 2 & 3\end{array}\right]$ What are the dimensions of matrix $ C$ ?
Solution: The first dimension is the number of rows in the matrix. How many rows does $ C$ have? The second dimension is the number of columns in the matrix. How many columns does $ C$ have? So, $ C$ is a 4 $\times$ 3 matrix.